Interventional
NeuroradiologyStenting and Angioplasty for Intracranial
Atherosclerotic Occlusive Disease
Nabil M. Akkawi and Ajay K. Wakhloo
Division of Neuroimaging and Intervention, University of Massachusetts Medical School,
Worcester, Massachusetts, U.S.A.2008
Table 1 Inclusion Criteria for Intracranial Stenting
>50% stenosis of a major intracranial vessel and refractory to
medical treatment
Minimum vessel diameter of 2.0 mm
Previous stroke
TIA
Neurological symptoms referable to the target lesion
Presence of symptoms during the 6 mo prior to treatment
Acute vessel occlusion or dissection after PTA
Abbreviations: TIA, transient ischemic attack; PTA, percutaneous
transluminal angioplasty.
Table 2 Exclusion Criteria for Intracranial Stenting
Severe neurological deficit from stroke
Chronic total occlusion
History of intracranial hemorrhage, hemorrhagic
stroke, major stroke, or any stroke with mass effect within 6 wk
of procedure
Contraindication for or resistant to antiplatelet therapy
RESTENOSIS AFTER STENTING
Stents may induce myointimal hyperplasia and restenosis
(Fig. 5). The restenosis rate after stenting of ICD
is approximately 10% to 13%. However, recently presented
data from several centers showed that at 6- and
12-month follow-up angiography study, WingSpan
self-expanding stents may have an incidence of up
to 40% in-stent stenosis. To address these issues, stents
coated with antiproliferative agents have been developed
to reduce the in-stent stenosis and are being
considered for the neurovascular system (58).
Sirolimus (rapamycin), an antifungal agent, and paclitaxel,
a microtubule inhibitor, have shown to prevent
neointimal proliferation and restenosis in the coronary
vessels when compared with bare metal stents (59).
These clinical results provided the impetus to study
the effect of antiproliferative agents for the intracranial
system. Levy et al. studied the effects of heparincoated
and sirolimus-eluting stents, which were
implanted in canine basilar arteries (60,61). The
mean percentage of stenosis 12 weeks after implantation
was less (12%) in the group with heparin-coated
stents compared with 22% in the group with uncoated
devices. Compared with bare-metal stents, the
sirolimus-coated devices did not impair endothelialization
and, furthermore, tended to reduce the proliferation
of smooth muscle cells. However, currently no
single appropriate animal model exists for the study of
intracranial atherosclerotic disease and of the effects of
drug-eluting devices.
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